This invention relates to a nut cracking mechanism, and in particular to a nut cracker, that accommodates a nut having a hard or brittle shell with a fragile meat, such as a walnut or pecan. The nut cracker is also of a type that accommodates nuts of varying size, thereby minimizing pre-sort operations.
Different nuts often require different types of mechanisms to effectively remove the shell from the internal kernel. This inventor has experience in devising nut cracking machines for the thick shell macadamia nut. Different nut cracking machines are disclosed in my patents including, Kim, U.S. Pat. No. 5,505,123, issued Apr. 9, 1996, for Nut Cracking Apparatus; and Fredericksen, et al., U.S. Pat. No. 5,247,879, issued Sep. 28, 1993, for Nut Cracking Machine.
Typically, a nut is compressed between two surfaces with sufficient force to crack or fracture the shell sufficiently to release the nut with minimum damage to the internal meat. Shelled nuts that are whole and undamaged command a greater sale price than fragmented nuts and nut pieces.
In a commercial nut shelling operation, a continuous feed of prepared nuts are supplied to one or more cracking and shelling machines which fracture the nut shell so that the nut can be separated from the shell. In general, separating the released meat from the shell and shell debris is accomplished in a subsequent stage from the cracking operation.
Certain nuts, such as walnuts and pecans, have brittle relatively thin shells. This class of nut has a bifurcated kernel with a fibrous membrane separating all but an interconnecting bridge between the two nearly identical halves. In the shelling operation, it is preferred that the kernel is split into halves in order that the membrane can be separated from the meat and discarded with the shells. For this class of nut, recovery of a minimally damaged half-kernel is preferred. Because of the thin brittle shells and irregularly shaped kernel, shelling of this type of nut with a high percentage of minimally damaged half-kernels is a challenge.